1. Field of the Invention
The present invention relates to an organic light-emitting compound and an organic electroluminescent (EL) device using the same, and more particularly, to an organic light-emitting compound which has superior electric features, thermostability, and photochemical stability, and can accomplish low driving voltage, high efficiency, and superior color purity of organic electroluminescent devices, and to an organic EL device using the same.
2. Description of the Related Art
An electroluminescent (EL) device is a self-emitting device which has a wide viewing angle, excellent contrast, and quick response time. EL devices can be classified into inorganic EL devices which use inorganic compounds for emissive layers and organic EL devices which use organic compounds for emissive layers. Compared to inorganic EL devices, organic EL devices have superior luminance, lower driving voltage, and quicker response time, and can realize multicolor images.
A typical organic EL device has a stacked structure in the form of an anode/organic emissive layer/cathode structure. Organic EL devices can also have an anode/hole-injection layer (HIL)/hole-transport layer (HTL)/emissive layer/electron-transport layer (ETL)/electron-injection layer (EIL)/cathode structure, or an anode/HIL/HTL/emissive layer/hole-blocking layer/ETL/EIL/cathode structure.
Materials used in organic EL devices can be classified into vacuum deposition materials and solution coating materials. Vacuum deposition materials should be able to have a vapor pressure of 10−6 torr or higher and may be small molecular materials having a molecular weight of 1200 or less. Solution coating materials should have sufficient solubility and usually include aromatic compounds or heterocyclic compounds.
Manufacturing organic EL devices using vacuum deposition increases costs due to the use of a vacuum system. In addition, when shadow mask is used to manufacture pixels for natural color display, manufacturing high resolution pixels is difficult.
On the other hand, manufacturing organic EL devices using solution coating methods such as inkjet printing, screen printing and spin coating is easy, costs less, and can accomplish relatively higher resolution than using shadow mask.
However, in terms of thermostability and color purity, blue light emitting molecules of solution coating materials are inferior to vacuum deposition materials. Also, as crystallization occurs after manufacturing, crystals as large as wavelengths of visible light disperse visible light and cause white residue. In addition, pinholes are formed and deteriorate the devices.
Japanese Patent No. 1999-003782 discloses two naphthyl-substituted anthracene compounds as compounds for emissive layers or hole injection layers. Also, Japanese Patent Nos. 2004-091334 and 2003-146951 disclose a triphenylamine-substituted anthracene compound for emissive layers or hole injection layers. However, solvent solubility of the above two compounds are not high enough to form layers and thus features of the resulting organic EL devices using the above two compounds are not satisfactory.
Thus, an organic EL device using blue light emitting compounds which are thermostable and suitable for forming layers, which has low driving voltage, superior luminance, high efficiency and superior color purity, is required.